Q: What causes color blindness?

The ability to accurately see colors depends on having three different types of color-detecting molecules located on cone-shaped cells with the retina detecting blue, green or red light. According to the National Eye Institute, color blindness is a genetic defect which leads to abnormalities in one or more cone cells. Red-green color blindness is the most common, followed by blue-yellow blindness. The complete absence of color vision, known as total color blindness, is rare.

Men are much more likely to be color blind, because the genes for the most common type of inherited color blindness are located on the X chromosome, and men have only one X chromosome. Women have two, and so even when one carries the defect, the other can compensate.

Color blindness can cause problems in daily life. Children may have trouble in school as many educational materials are color-coded. Distinguishing yellow chalk on a green chalkboard can be particularly difficult.

Adults can struggle with traffic lights, knowing when meat is cooked to the desired color or picking ripe fruit.

Those with red-green color blindness may be able to use special lenses that help them distinguish colors, and new phone apps can help properly identify colors.

Researchers have been testing ways to treat color blindness, including using gene therapy to cure blindness in adult monkeys. But such treatments are not yet ready for use in humans.